I'm looking to buy a set of headers and possibly cats. Where I live, I am not required to pass emissions or noise tests. What would you guys recommend? What size headers? Should I even buy cats? What would hi-flow cats do for me anyways?

I have a catback Dynomax exhaust. I installed them with out the mufflers though. Any recommendations?

I keep wondering why people spend money on a cat back and then eliminate the mufflers?
! 7/8" long tubes are the norm. As for hi flo cats..........depends on how raspy you want your exhaust. The cats will mellow the rasp. There are plenty of good quality headers out there, just read some threads and visit our vendors.

If ur looking for a set of headers and cats i would recommend Kooks or American Racing Headers (ARH). I personaly just installed a set of Kooks long tube headers along with their highflowcats and i love the fit, finish and quality of them. If ur planning to keep ur car stock and just add some headers and exhaust the 1 3/4 headers will work. If ur planning to do more mods in the future then 1 7/8 is the way to go (thats what i have) and if ur planning to go with high horsepower #s like a big supercharger than 2 inch will be best. U can't go wrong with a 1 7/8 inch set of headers. That is what i recommend. If u get a set of headers i recommend u get them coated also so u hood keep the under the hood temps a bit lower as they help to do that plus it also gives ur car that extra eye candy under the hood. PM me if u want me to tell u where u can get a set of headers with cats for an unbelievable price!!!! u can get a set of Kooks headers coated but i think ARH doesnt coat theirs. U can always get them coated tho! I would recommend cats unless ur car is supecharged then i would say no. The Kooks high flow cats are really high flow and.u can even see light through them. They help ur car not smell like an old muscle car. The cats flow very well that u probabpy wont gain much hp if u dont run them. And just warning u, once u do headers ur car will be LOUD !! It will sound bad azz! And in order to get the full benefit.of them.u will have to tune ur car. I love mine.!! Pm me and i can hook u up.with a set for a great price. Do it once and do it right!!!

Well I bought the car with the catback on it but took the mufflers off cause I wanted it a little deeper and louder. So if I don't want it to be raspy, I should add hi-flow cats? Or just regular cats?

With headers, always high flow cats....not stock cats. Im only speaking from my experience. '04 GTO: full stainless works 3" w/turbo mufflers and hi flow cats. 1 3/4" long tubes. Sounded nice and stock at idle. Nice low tone when opened up. '06 GTO stainless works 1 3/4" long tubes and stock cat back, no hi flow cats. Had a good sound at idle and low rpm. But when you got into it, it was raspy.
I find the cats mellow the tone in the higher rpm. An x-pipe will also mellow it some.

Do this. With the mufflers... you'll question whether or not it's too loud. Then you'll ultimately decide your car sounds bad f*cking a$$, and be very happy with your decision-making ability. My muffler deleted catback is still up on the shelf at the shop where it belongs...